Streaming media resource downloading method and apparatus, and terminal device

ABSTRACT

A streaming media resource downloading method includes: determining that a first media file is a to-be-downloaded media file according to first network bandwidth, where the first media file is included in a streaming media resource corresponding to the first network bandwidth, and the first media file includes N data blocks; and after an (n−1) th  data block in the first media file is downloaded, and before an n th  data block in the first media file is downloaded, determining a length of the to-be-downloaded n th  data block according to network bandwidth reduction times in an executed first media file downloading process, where 1≦n≦N. Therefore, a length of a to-be-downloaded data block is adjusted according to the network bandwidth reduction times in the first media file downloading process, so that video playing can better adapt to a bandwidth change, and streaming media resource switching times are reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/CN2015/074694, filed on Mar. 20, 2015, which is hereby incorporatedby reference in its entirety.

TECHNICAL FIELD

Embodiments of the present invention relate to the field of networktransmission, and in particular, to a streaming media resourcedownloading method and apparatus, and a terminal device.

BACKGROUND

HTTP (HyperText Transfer Protocol, Hypertext Transfer Protocol) LiveStreaming (HLS) is an HTTP-based streaming media network transmissionprotocol put forward by Apple. A streaming media is a media playingformat on a network in a streaming transmission manner. A principle ofthe HLS protocol is dividing a streaming media resource into multipleHTTP-based TS (Transport Stream, transport stream) media files with asame time length for transmission. Each TS media file in a streamingmedia resource is independent, and multiple TS media files form oneconsecutive streaming media resource. When a terminal device plays astreaming media resource located on a network side, the terminal deviceattempts to match, according to detected network bandwidth, acorresponding streaming media resource for downloading. When the networkbandwidth changes, a client attempts tore-match, according to changednetwork bandwidth, a streaming media resource for downloading.

When network bandwidth changes within a large range or frequentlyfluctuates, a detected network bandwidth value and an actual networkbandwidth value have a relatively large difference. However, to adapt toa network bandwidth change, a terminal device still attempts tofrequently match a new streaming media resource according to a detectednetwork bandwidth value for downloading. Therefore, a downloadedstreaming media resource may not match actual network bandwidth, andfurther video playing is not smooth.

SUMMARY

Embodiments of the present invention provide a streaming media resourcedownloading method and apparatus, and a terminal device, so as to reducestreaming media resource switching times when network bandwidth changeswithin a large range or frequently fluctuates, so that video playing issmooth.

According to a first aspect, a streaming media resource downloadingmethod is provided, including:

determining that a first media file is a to-be-downloaded media fileaccording to first network bandwidth, where the first network bandwidthis network bandwidth when it is determined that the first media file isa to-be-downloaded media file; and the first media file is included in astreaming media resource corresponding to the first network bandwidth,and the first media file includes N data blocks, where N≧2, and N is aninteger; and

after an (n−1)^(th) data block in the first media file is downloaded,and before an n^(th) data block in the first media file is downloaded,determining a length of the to-be-downloaded n^(th) data block accordingto network bandwidth reduction times in an executed first media filedownloading process, where 1≧n≧N.

In a first possible implementation manner of the first aspect, themethod further includes:

periodically detecting network bandwidth in the first media filedownloading process; and

obtaining the network bandwidth reduction times in the executed firstmedia file downloading process according to the periodically detectednetwork bandwidth.

With reference to the first aspect or the first possible implementationmanner of the first aspect, in a second possible implementation manner,the determining a length of the to-be-downloaded n^(th) data blockaccording to network bandwidth reduction times in an executed firstmedia file downloading process specifically includes:

when the network bandwidth reduction times in the executed first mediafile downloading process are equal to 0, determining that the length ofthe to-be-downloaded n^(th) data block is a preset length, where thepreset length is corresponding to the first media file; or

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than 0 and less than a firstthreshold, determining that the length of the to-be-downloaded n^(th)data block is less than the preset length.

With reference to the second possible implementation manner of the firstaspect, in a third possible implementation manner, the method furtherincludes: when the network bandwidth reduction times in the executedfirst media file downloading process are greater than 0 and less thanthe first threshold, using the following rules to determine the lengthof the to-be-downloaded n^(th) data block:

when there are more network bandwidth reduction times in the executedfirst media file downloading process, determining that the length of then^(th) data block is smaller; or

when there is a larger time difference between a current moment and amoment of starting to download the first media file, determining thatthe length of the n^(th) data block is smaller.

With reference to the first aspect or any one of the possibleimplementation manners of the first aspect, in a fourth possibleimplementation manner, after the determining a length of theto-be-downloaded n^(th) data block, the method further includes:

downloading the n^(th) data block according to the determined length ofthe n^(th) data block.

With reference to the first aspect or any one of the possibleimplementation manners of the first aspect, in a fifth possibleimplementation manner, the method further includes:

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than or equal to the firstthreshold, stopping downloading the first media file; and

determining that a second media file is a to-be-downloaded media fileaccording to second network bandwidth, where the second networkbandwidth is network bandwidth when it is determined that the networkbandwidth reduction times are greater than or equal to the firstthreshold; and

the second media file is included in a streaming media resourcecorresponding to the second network bandwidth.

With reference to any one of the possible implementation manners of thefirst aspect, in a sixth possible implementation manner, the methodfurther includes: when the network bandwidth in the first media filedownloading process is periodically detected, determining a detectionperiod in the following manner:

when i−x≧k, determining that T_(m+1)>T; or

when 0≦i−x<k, determining that T_(m+1)=T;

where i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, bandwidth corresponding to iis greater than bandwidth corresponding to x, and k is a preset secondthreshold; and

T is a preset detection period, and T_(m+1) is a network bandwidthdetection period at an (m+1)^(th) time, where T_(m+1)=t_(m+1)−t_(m),t_(m+1) is a network bandwidth detection moment at the (m+1)^(th) time,and t_(m) is a network bandwidth detection moment at the m^(th) time.

With reference to any one of the possible implementation manners of thefirst aspect, in a seventh possible implementation manner, the methodfurther includes: obtaining the network bandwidth reduction timesaccording to the following rules:

-   -   when i−x>0, increasing the network bandwidth reduction times by        1, where

i is the bandwidth level corresponding to the first network bandwidth,and x is the bandwidth level corresponding to the network bandwidthdetected at the m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, and the bandwidthcorresponding to i is greater than the bandwidth corresponding to x.

With reference to the sixth possible implementation manner or theseventh possible implementation manner of the first aspect, in an eighthpossible implementation manner, the method further includes:determining, in the following manner, a bandwidth level corresponding toa detected network bandwidth:

the streaming media resource includes multiple media files that arerespectively corresponding to different bandwidth levels;

each bandwidth level is corresponding to one network bandwidththreshold; and

when W_(i)×a≦w_(detected)<W_(i+1)×b, it is determined that the bandwidthlevel corresponding to the detected network bandwidth is i, where

W_(detected) is the detected network bandwidth, W_(i) is a networkbandwidth threshold corresponding to the bandwidth level i, and W_(i+1)is a network bandwidth threshold corresponding to a bandwidth level i+1,where 0<a<1, and 0<b<1.

According to a second aspect, a streaming media resource downloadingapparatus is provided, including:

a first determining unit, configured to determine that a first mediafile is a to-be-downloaded media file according to first networkbandwidth, where the first network bandwidth is network bandwidth whenit is determined that the first media file is a to-be-downloaded mediafile; and the first media file is included in a streaming media resourcecorresponding to the first network bandwidth, and the first media fileincludes N data blocks, where N≧2, and N is an integer;

a reduction times obtaining unit, configured to obtain network bandwidthreduction times in an executed first media file downloading process; and

a second determining unit, configured to: after an (n−1)^(th) data blockin the first media file is downloaded, and before an n^(th) data blockin the first media file is downloaded, determine a length of theto-be-downloaded n^(th) data block according to the network bandwidthreduction times that are in the executed first media file downloadingprocess and that are obtained by the reduction times obtaining unit,where 1≦n≦N.

In a first possible implementation manner of the second aspect, theapparatus further includes:

a detection unit, configured to periodically detect network bandwidth inthe first media file downloading process; and

the reduction times obtaining unit is specifically configured to obtainthe network bandwidth reduction times in the executed first media filedownloading process according to the network bandwidth periodicallydetected by the detection unit.

With reference to the second aspect or the first possible implementationmanner of the second aspect, in a second possible implementation manner,when determining the length of the to-be-downloaded n^(th) data blockaccording to the network bandwidth reduction times that are in theexecuted first media file downloading process and that are obtained bythe reduction times obtaining unit, the second determining unit isspecifically configured to:

when the network bandwidth reduction times in the executed first mediafile downloading process are equal to 0, determine that the length ofthe to-be-downloaded n^(th) data block is a preset length, where thepreset length is corresponding to the first media file;

or when the network bandwidth reduction times in the executed firstmedia file downloading process are greater than 0 and less than a firstthreshold, determine that the length of the to-be-downloaded n^(th) datablock is less than the preset length.

With reference to the second possible implementation manner of thesecond aspect, in a third possible implementation manner, when thenetwork bandwidth reduction times in the executed first media filedownloading process are greater than 0 and less than the firstthreshold, the second determining unit uses the following rules todetermine the length of the to-be-downloaded n^(th) data block:

when there are more network bandwidth reduction times in the executedfirst media file downloading process, determining that the length of then^(th) data block is smaller; or

when there is a larger time difference between a current moment and amoment of starting to download the first media file, determining thatthe length of the n^(th) data block is smaller.

With reference to the second aspect or any one of the possibleimplementation manners of the second aspect, in a fourth possibleimplementation manner, the apparatus further includes:

a data block downloading unit, configured to: after the seconddetermining unit determines the length of the to-be-downloaded n^(th)data block, download the n^(th) data block according to the length, ofthe n^(th) data block, determined by the second determining unit.

With reference to the second aspect or any one of the possibleimplementation manners of the second aspect, in a fifth possibleimplementation manner,

the second determining unit is further configured to: after the(n−1)^(th) data block in the first media file is downloaded, before then^(th) data block in the first media file is downloaded, and when thenetwork bandwidth reduction times in the executed first media filedownloading process are greater than or equal to the first threshold,stop downloading the first media file; and

the first determining unit is further configured to determine that asecond media file is a to-be-downloaded media file according to secondnetwork bandwidth, where the second network bandwidth is networkbandwidth when it is determined that the network bandwidth reductiontimes are greater than or equal to the first threshold; and the secondmedia file is included in a streaming media resource corresponding tothe second network bandwidth.

With reference to any one of the possible implementation manners of thesecond aspect, in a sixth possible implementation manner, the apparatusfurther includes a period calculation unit, configured to calculate adetection period of periodic network bandwidth detection in the firstmedia file downloading process, and the period calculation unitdetermines the detection period in the following manner:

when i−x>k, determining that T_(m+1)>T; or

when 0≦i−x<k, determining that T_(m+1)=T;

where i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, bandwidth corresponding to iis greater than bandwidth corresponding to x, and k is a preset secondthreshold; and

T is a preset detection period, and T_(m+1) is a network bandwidthdetection period at an (m+1)^(th) time, where T_(m+1)=t_(m+1)−t_(m),t_(m+1) is a network bandwidth detection moment at the (m+1)^(th) time,and t_(m) is a network bandwidth detection moment at the m^(th) time.

With reference to any one of the possible implementation manners of thesecond aspect, in a seventh possible implementation manner, whenobtaining the network bandwidth reduction times in the executed firstmedia file downloading process, the reduction times obtaining unitobtains the network bandwidth reduction times according to the followingrules:

when i−x>0, increasing the network bandwidth reduction times by 1, where

i is the bandwidth level corresponding to the first network bandwidth,and x is the bandwidth level corresponding to the network bandwidthdetected at the m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, and the bandwidthcorresponding to i is greater than the bandwidth corresponding to x.

With reference to the sixth or the seventh possible implementationmanner of the second aspect, in an eighth possible implementationmanner, the apparatus further includes a bandwidth level determiningunit, where

the bandwidth level determining unit is configured to determine, in thefollowing manner, a bandwidth level corresponding to a network bandwidthdetected by the detection unit;

the streaming media resource includes multiple media files that arerespectively corresponding to different bandwidth levels;

each bandwidth level is corresponding to one network bandwidththreshold; and

when W_(i)×a≦W_(detected)<W_(i+1)×b, it is determined that the bandwidthlevel corresponding to the detected network bandwidth is i, where

W_(detected) is the detected network bandwidth, W_(i) is a networkbandwidth threshold corresponding to the bandwidth level i, and W_(i+1)is a network bandwidth threshold corresponding to a bandwidth level i+1,where 0<a<1, and 0<b<1.

According to a third aspect, a terminal device is provided, including:

a processor;

a data storage apparatus; and

a communications interface, where

the processor, the data storage apparatus, and the communicationsinterface communicate with each other by using a bus; and

the processor reads program code and data that are stored in the datastorage apparatus, so as to execute the following operations:

determining that a first media file is a to-be-downloaded media fileaccording to first network bandwidth, where the first network bandwidthis network bandwidth when it is determined that the first media file isa to-be-downloaded media file; and the first media file is included in astreaming media resource corresponding to the first network bandwidth,and the first media file includes N data blocks, where N≦2, and N is aninteger; and

after an (n−1)^(th) data block in the first media file is downloaded,and before an n^(th) data block in the first media file is downloaded,determining a length of the to-be-downloaded n^(th) data block accordingto network bandwidth reduction times in an executed first media filedownloading process, where 1≦n≦N.

In a first possible implementation manner of the third aspect, theprocessor further executes the following operations:

periodically detecting network bandwidth in the first media filedownloading process; and

obtaining the network bandwidth reduction times in the executed firstmedia file downloading process according to the periodically detectednetwork bandwidth.

With reference to the third aspect or the first possible implementationmanner of the third aspect, in a second possible implementation manner,when determining the length of the to-be-downloaded n^(th) data blockaccording to the network bandwidth reduction times in the executed firstmedia file downloading process, the processor specifically executes thefollowing operations:

when the network bandwidth reduction times in the executed first mediafile downloading process are equal to 0, determining that the length ofthe to-be-downloaded n^(th) data block is a preset length, where thepreset length is corresponding to the first media file; or

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than 0 and less than a firstthreshold, determining that the length of the to-be-downloaded n^(th)data block is less than the preset length.

With reference to the second possible implementation manner of the thirdaspect, in a third possible implementation manner, when the networkbandwidth reduction times in the executed first media file downloadingprocess are greater than 0 and less than the first threshold, theprocessor uses the following rules to determine the length of theto-be-downloaded n^(th) data block:

when there are more network bandwidth reduction times in the executedfirst media file downloading process, determining that the length of then^(th) data block is smaller; or

when there is a larger time difference between a current moment and amoment of starting to download the first media file, determining thatthe length of the n^(th) data block is smaller.

With reference to the third aspect or any one of the possibleimplementation manners of the third aspect, in a fourth possibleimplementation manner, after determining the length of theto-be-downloaded n^(th) data block, the processor executes, according tothe determined length of the n^(th) data block, an operation ofdownloading the n^(th) data block.

With reference to the third aspect or any one of the possibleimplementation manners of the third aspect, in a fifth possibleimplementation manner, the processor further executes the followingoperations:

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than or equal to the firstthreshold, stopping downloading the first media file; and

determining that a second media file is a to-be-downloaded media fileaccording to second network bandwidth, where the second networkbandwidth is network bandwidth when it is determined that the networkbandwidth reduction times are greater than or equal to the firstthreshold; and the second media file is included in a streaming mediaresource corresponding to the second network bandwidth.

With reference to any one of the possible implementation manners of thethird aspect, in a sixth possible implementation manner, whenperiodically detecting the network bandwidth in the first media filedownloading process, the processor determines a detection period in thefollowing manner:

when i−x≧k, determining that T_(m+1)>T; or

when 0≦i−x<k, determining that T_(m+1)=T;

where i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, bandwidth corresponding to iis greater than bandwidth corresponding to x, and k is a preset secondthreshold; and

T is a preset detection period, and T_(m+1) is a network bandwidthdetection period at an (m+1)^(th) time, where T_(m+1)=t_(m+1)−t_(m),t_(m+1) is a network bandwidth detection moment at the (m+1)^(th) time,and t_(m) is a network bandwidth detection moment at the m^(th) time.

With reference to any one of the possible implementation manners of thethird aspect, in a seventh possible implementation manner, the processorobtains the network bandwidth reduction times according to the followingrules:

when i−x>0, increasing the network bandwidth reduction times by 1, where

i is the bandwidth level corresponding to the first network bandwidth,and x is the bandwidth level corresponding to the network bandwidthdetected at the m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, and the bandwidthcorresponding to i is greater than the bandwidth corresponding to x.

With reference to the sixth or the seventh possible implementationmanner of the third aspect, in an eighth possible implementation manner,the processor determines, in the following manner, a bandwidth levelcorresponding to a detected network bandwidth:

the streaming media resource includes multiple media files that arerespectively corresponding to different bandwidth levels;

each bandwidth level is corresponding to one network bandwidththreshold; and

when W_(i)×a≦W_(detected)<W_(i+1)×b, it is determined that the bandwidthlevel corresponding to the detected network bandwidth is i, where

W_(detected) is the detected network bandwidth, W_(i) is a networkbandwidth threshold corresponding to the bandwidth level i, and W_(i+1)is a network bandwidth threshold corresponding to a bandwidth level i+1,where 0<a<1, and 0<b<1.

In the embodiments of the present invention, after it is determined thata first media file is a to-be-downloaded media file, when the firstmedia file is divided into blocks for downloading, a length of ato-be-downloaded data block is determined according to network bandwidthreduction times in a first media file downloading process, so as toadapt to reduced network bandwidth, so that streaming media playing canbetter adapt to a network bandwidth change, streaming media resourceswitching times are reduced, and video playing is smooth.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart of a streaming media resource downloading methodaccording to an embodiment of the present invention;

FIG. 2 is a flowchart of a method for obtaining network bandwidthreduction times according to an embodiment of the present invention;

FIG. 3 is a flowchart of another streaming media resource downloadingmethod according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a streaming media resource downloadingapparatus according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of another streaming media resourcedownloading apparatus according to an embodiment of the presentinvention; and

FIG. 6 is a schematic diagram of a terminal device according to anembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are merely some but not all of the embodiments ofthe present invention. All other embodiments obtained by persons ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

It should be understood that, when ordinal numbers such as “first” and“second” are mentioned in the embodiments of the present invention, theyare merely used for distinguishing unless they definitely show asequence according to a context.

A streaming media resource downloading method provided in theembodiments of the present invention mainly refers to streaming mediaresource downloading based on an HLS live streaming transfer protocol. Astreaming media resource mentioned in the embodiments of the presentinvention generally refers to any file related to an HLS transfer file,and may be a general name of all files, or may be any one of transferfiles.

FIG. 1 is a flowchart of a streaming media resource downloading methodaccording to an embodiment of the present invention. As shown in FIG. 1,the method includes the following steps.

Step 101: Determine that a first media file is a to-be-downloaded mediafile according to first network bandwidth.

In this embodiment of the present invention, when preparing to downloada streaming media resource, a terminal device may obtain current networkbandwidth, that is, the first network bandwidth. That is, the firstnetwork bandwidth is network bandwidth when it is determined that thefirst media file is a to-be-downloaded media file. Then the terminaldevice may obtain a bandwidth level and an index value that are of astreaming media resource corresponding to the first network bandwidth,and determine that the first media file in the streaming media resourceis a to-be-downloaded media file. The first media file is included inthe streaming media resource corresponding to the first networkbandwidth, and the first media file includes N data blocks, where N≧2,and N is an integer.

Generally, a streaming media resource file includes an index file and anMPEG2-TS (Moving Picture Experts Group 2-Transport Stream, MovingPicture Experts Group 2-Transport Stream, TS or MTS for short) mediafile. A TS is a standard format for transmission and storage of variousdata including sound effect, a video, and a communications protocol, andis used in a digital video broadcasting system. The index file includesmultiple sub-index files, and conditions for downloading and playing astreaming media resource are stipulated in each sub-index file, such asBANDWIDTH (bandwidth), RESOLUTION (resolution), and a file name. Eachstreaming media resource includes multiple TS media files, and these TSmedia files are consecutive in terms of time to form one completestreaming media resource. In addition, each TS media file includesmultiple data blocks. It may be understood that each streaming mediaresource is downloaded in a unit of a TS media file, and each TS mediafile is downloaded in a unit of a data block. The TS media file is theforegoing first media file.

The TS media file described in this embodiment of the present inventionincludes at least two data blocks, and during downloading of the TSmedia file, the data blocks are successively downloaded, instead ofentirely downloading the TS media file. Lengths of the multiple datablocks may be fixed, or may be changeable. The lengths of the multipledata blocks may be equal, or may be unequal.

An index file of a streaming media resource includes multiple sub-indexfiles that may be in the following format, for example. The followinglists only one sub-index file to represent a general format of allsub-index files:

#EXT-X-STREAM-INF: PROGRAM-ID=?, BANDWIDTH=?, RESOLUTION=?, CODECS=“?”

i.m3u8

where #EXT-X-STREAM-INF is an attribute information flag bit of astreaming media resource that is represented by a sub-index file;PROGRAM-ID refers to an identifier of the streaming media resource, andis used to represent a same type of resources of different encodingformats; BANDWIDTH refers to a network bandwidth threshold suitable forplaying the streaming media resource, and a unit is bit/s; RESOLUTIONrefers to resolution; CODECS refers to a type and a format of thestreaming media resource; i.m3u8 is a file name of the sub-index file,where i is an integer greater than or equal to 0 and represents an indexvalue and a bandwidth level of the sub-index file, and larger iindicates a larger index value, a higher bandwidth level, and largerbandwidth.

When preparing to download a streaming media resource, the terminaldevice may obtain the first network bandwidth by using a bandwidthestimation method, for example.

For example, the bandwidth estimation method is:

recording a length and a time of a downloaded data block during eachHTTP connection before a current moment, and storing latest multipledownloading records before the current time, for example, 100 records,and entering lengths and times of downloaded data blocks in the latest100 records to formula 1, to obtain first network bandwidth W₁:

W ₁=(B ₁ +B ₂ + . . . +B _(n))×8×1000/(T ₁ +T ₂ + . . . +T_(n))(bit/s)  Formula 1

where B_(n) is a length of a downloaded data block in an n^(th) record,and a unit is KB; and T_(n) is a time taken to download the data blockin the n^(th) record, and a unit is ms, where 2≦n≦100.

The first network bandwidth W₁ is compared with a network bandwidththreshold of each sub-index file, so as to determine a streaming mediaresource which the first network bandwidth W₁ is suitable for playing,and a bandwidth level of a sub-index file corresponding to the firstnetwork bandwidth W₁.

A determining method may use the following manner:

When BANDWIDTH_(i)≦BANDWIDTH_(i+1), it is determined that the firstnetwork bandwidth W₁ is suitable for downloading a streaming mediaresource corresponding to BANDWIDTH_(i), and a bandwidth level of thestreaming media resource corresponding to W₁ is i; or when BANDWIDTH_(i)is a maximum value in network bandwidth thresholds of all sub-indexfiles, if W₁≧BANDWIDTH_(i), it is determined that the first networkbandwidth W₁ is suitable for downloading a streaming media resourcecorresponding to BANDWIDTH_(i), and a bandwidth level of the streamingmedia resource corresponding to W₁ is i, where BANDWIDTH_(i) is anetwork bandwidth threshold of a sub-index file whose index value is i.

A streaming media resource whose index value is i includes multiple TSmedia files, and each TS media file includes at least two data blocks.When determining that the first network bandwidth W₁ is corresponding tothe streaming media resource whose index value is i, the terminal devicedetermines that in the streaming media resource, a TS media file whoseindex value is i, that is, the first media file, is a to-be-downloadedmedia file, and prepares to download the first media file. It should benoted that in the streaming media resource, there are multiple TS mediafiles whose index values are i, and in a specific implementationprocess, one suitable to-be-downloaded TS media file may be selectedfrom the multiple TS media files according to an existing mechanism.

Step 102: After an (n−1)^(th) data block in the first media file isdownloaded, and before an n^(th) data block in the first media file isdownloaded, determine a length of the to-be-downloaded n^(th) data blockaccording to network bandwidth reduction times in an executed firstmedia file downloading process, where 1≦n≦N.

In a process of downloading the first media file by dividing the firstmedia file into multiple data blocks, the terminal device may adjust alength of a to-be-downloaded data block according to a network bandwidthchange.

It should be noted that each first media file may be corresponding toone preset length of a data block. For example, when the preset length,of the data block, corresponding to the first media file is L1, duringdownloading of the first media file, the first media file is dividedinto multiple data blocks with a length of L1 by default fordownloading. Then in a downloading process, a length of ato-be-downloaded data block may be adjusted according to a networkbandwidth change. The preset length, of the data block, corresponding tothe first media file is related to a network bandwidth thresholdcorresponding to the first media file (that is, the preset length, ofthe data block, corresponding to the first media file is related to anindex value corresponding to the first media file), and a higher networkbandwidth threshold corresponding to the first media file (that is, alarger index value corresponding to the first media file) indicates agreater preset length, of the data block, corresponding to the firstmedia file.

After it is determined that the first media file is a to-be-downloadedmedia file, a preset length is used to start to download the first datablock in the first media file, that is, a length of the first data blockis the preset length. During downloading of the first data block,network bandwidth reduction times do not need to be determined; or itmay be understood as follows: Before the first data block is downloaded,obtained network bandwidth reduction times are 0, and in this case, itis determined that the length of the to-be-downloaded first data blockis the preset length. It should be noted that when the length of thefirst data block is determined, n=1, and in this case, the (n−1)^(th)data block is a 0^(th) data block, and the 0^(th) data block is emptyand does not include any content.

When it is determined that the first media file in the streaming mediaresource whose index value is i is a to-be-downloaded media fileaccording to step 101, the preset length, of the data block,corresponding to the first media file may be obtained according to anetwork bandwidth threshold of a sub-index file whose index value is i.

For example, the preset length of the data block may be obtained byusing formula 2:

P _(i)=Log₂(BANDWIDTH_(i)/BANDWIDTH_(min))×10240  Formula 2

where P_(i) is the preset length, of the data block, corresponding tothe first media file whose index value is i, and P_(min)≦Pi≦P_(max),where P_(min) is a minimum value of the preset length, P_(max) is amaximum value of the preset length, and P_(min) and P_(max) may bedetermined according to an actual situation. For example, P_(min)=10240,and P_(max)=655360. BANDWIDTH_(min) is a minimum value in networkbandwidth thresholds of all sub-index files.

When it is determined that the streaming media resource whose indexvalue is i is corresponding to the first network bandwidth W₁, the firstdata block in the first media file in the streaming media resourcestarts to be downloaded by using P_(i) as the preset length.

Before any another data block in the first media file is downloaded, alength of a to-be-downloaded data block is determined according to thenetwork bandwidth reduction times in the executed first media filedownloading process. For example, after the (n−1)^(th) data block in thefirst media file is downloaded, and before the n^(th) data block in thefirst media file is downloaded, the length of the to-be-downloadedn^(th) data block is determined according to the network bandwidthreduction times in the executed first media file downloading process.The executed first media file downloading process is a process ofdownloading (n−1) data blocks in the first media file, where the (n−1)data blocks may be a 0^(th) data block, a first data block, a secondblock, . . . , and the (n−1)^(th) data block.

The length of the n^(th) data block is determined according to thenetwork bandwidth reduction times in the first media file downloadingprocess, and the determined length may be equal to the preset length ofthe data block or less than the preset length of the data block, so thatmedia file downloading can adapt to a requirement, of reduced networkbandwidth, on a length of a to-be-downloaded data block.

In the first media file downloading process, network bandwidth maychange within a large range or frequently fluctuate. When the networkbandwidth is reduced, a data volume that can be downloaded in a specifictime is reduced with relatively low network bandwidth. If the presetlength is still used to download a data block, a downloading speeddecreases, and downloading may even stop because the network bandwidthconstantly decreases. If the media file is directly switched, accordingto reduced network bandwidth, to a new media file for downloading,inaccurate resource switching is caused because of inaccurate networkbandwidth detection. In addition, frequent network bandwidth fluctuationcauses frequent resource switching, causing a resource waste.

In this embodiment of the present invention, after it is determined thata first media file is a to-be-downloaded media file, the first mediafile is divided into blocks for downloading. Before any data block inthe first media file is downloaded, a length of a to-be-downloaded datablock is determined according to network bandwidth reduction times in anexecuted first media file downloading process. Therefore, the length ofthe to-be-downloaded data block adapts to reduced network bandwidth,times of downloading resource switching can be reduced, and videoplaying is smooth.

FIG. 2 is a flowchart of a method for obtaining network bandwidthreduction times according to an embodiment of the present invention. Themethod is used to obtain the network bandwidth reduction times in theexecuted first media file downloading process in the embodiment shown inFIG. 1.

As shown in FIG. 2, the method includes the following steps.

Step 201: Periodically detect network bandwidth in a first media filedownloading process.

In the first media file downloading process, a terminal deviceconstantly and periodically detects the network bandwidth to obtaindetected network bandwidth.

It should be noted that a period mentioned in this embodiment of thepresent invention is a time difference between two adjacent networkbandwidth detection moments, and the period is adjustable and is notfixed. Both a period and a time point of executing network bandwidthdetection are unrelated to a to-be-downloaded data block, anddownloading moments in the first media file downloading process are usedas an executing basis.

For example, a detection period of periodic detection may be determinedin the following manner:

The detection period of periodic network bandwidth detection is presetto T_(preset), and after downloading of the first media file starts, aperiod of executing network bandwidth detection for the first time isT_(preset), that is, network bandwidth detection is executed for thefirst time when a time difference between a moment of starting todownload the first media file and a current time is T_(preset).

Detected network bandwidth obtained by executing periodic networkbandwidth detection is W_(detected), and it is determined, according tothe method of determining the bandwidth level, of the sub-index file,corresponding to the first network bandwidth W₁ in step 101, thatW_(detected) is corresponding to a bandwidth level of a sub-index filewhose index value is x. In addition, if it is learned that the firstnetwork bandwidth W₁ obtained when the to-be-downloaded first media fileis determined is corresponding to the bandwidth level of the sub-indexfile whose index value is i, determining is performed on a relationshipbetween the index value i and the index value x.

A larger index value indicates higher network bandwidth corresponding tothe index value; and a threshold k of a difference value of indexvalues, that is, a preset second threshold, is greater than 0. Wheni−x≧k, it indicates that the detected network bandwidth W_(detected)obtained by means of periodic detection is reduced relative to the firstnetwork bandwidth W₁, and the detection period of periodic networkbandwidth detection may be increased, that is, a period of executingnetwork bandwidth detection for the next time T_(n+1)>T_(preset); or ifi−x<k, it indicates that the detected network bandwidth W_(detected)obtained by means of periodic detection is not reduced relative to thefirst network bandwidth W₁, and the detection period of periodic networkbandwidth detection does not change, that is, a period of executingnetwork bandwidth detection for the next time T_(n+1)=T_(preset).

The terminal device adjusts the detection period of periodic networkbandwidth detection in the first media file downloading processaccording to an index value of the periodically detected networkbandwidth, and executes a next time of network bandwidth detection in anadjusted detection period of periodic network bandwidth detection toobtain periodically detected network bandwidth.

Step 202: Obtain network bandwidth reduction times in the executed firstmedia file downloading process according to the periodically detectednetwork bandwidth.

The detected network bandwidth W_(detected) is obtained by periodicallydetecting the network bandwidth in the first media file downloadingprocess according to step 201. The detected network bandwidthW_(detected) is corresponding to the bandwidth level of the sub-indexfile whose index value is x, and the first network bandwidth W₁ iscorresponding to the bandwidth level of the sub-index file whose indexvalue is i. If i>x, that is, if the detected network bandwidth isreduced compared with the first network bandwidth, the network bandwidthreduction times in the first media file downloading process areincreased by 1.

In the first media file downloading process, each time periodic networkbandwidth detection is executed, whether the detected network bandwidthis reduced is determined according to the periodically detected networkbandwidth W_(detected), and detected reduction times are accumulated inthe network bandwidth reduction times in the first media filedownloading process.

In the first media file downloading process, the network bandwidth maychange within a large range or frequently fluctuate, and the detectednetwork bandwidth may be lower or higher than actual network bandwidth.Consequently, the terminal device inaccurately switches ato-be-downloaded file according to an inaccurate network bandwidthdetection value.

In this embodiment of the present invention, when network bandwidthdetection is periodically executed, and a difference between a bandwidthlevel of periodically detected network bandwidth and a bandwidth levelof a first network bandwidth exceeds a specific threshold, that is, whenit is determined that in a first media file downloading process,changing of the network bandwidth reaches a specific degree, a detectionperiod is accordingly increased. Therefore, a network bandwidth valueclose to an actual value can be obtained by extending the detectionperiod, so that a difference of a network bandwidth estimation result isreduced, and an estimation result of detected network bandwidth is moreaccurate.

It should be noted that in this embodiment of the present invention,when the detection period in periodic detection is determined in step201, and the network bandwidth reduction times in the executed firstmedia file downloading process are obtained in step 202, the bandwidthlevel of the periodically detected network bandwidth needs to bedetermined.

In this embodiment of the present invention, a method for determiningthe bandwidth level of the periodically detected network bandwidth mayuse the method for determining the bandwidth level, of the sub-indexfile, corresponding to the first network bandwidth provided in step 101,or the following method may be used to replace the method fordetermining the bandwidth level in step 101.

In this embodiment of the present invention, for example, a networkbandwidth threshold of each sub-index file of a streaming media resourcemay be adjusted to a specific degree, so as to buffer a switch point ofthe streaming media resource when network bandwidth is periodicallydetected in a first media file downloading process. In addition, ahigher bandwidth level indicates a larger adjustment degree of a networkbandwidth threshold.

A streaming media resource includes multiple streaming media resourceshaving different network bandwidth thresholds. A network bandwidththreshold is included in a sub-index file of a streaming media resource,and is corresponding to a bandwidth level of the streaming mediaresource. When W₁×a≦W_(detected)<W_(i+1)×b, it is determined that thebandwidth level corresponding to the detected network bandwidthW_(detected) is i. It may be understood that when W_(i) is a maximumvalue of the network bandwidth thresholds, W_(i+1) may be equal toinfinity. Therefore, provided that W_(detected)>W_(i)×a, it may bedetermined that the bandwidth level corresponding to the detectednetwork bandwidth is i. W_(i) is a network bandwidth thresholdcorresponding to the bandwidth level i, and W_(i+1) is a networkbandwidth threshold corresponding to a bandwidth level i+1, where 0<a<1,and 0<b<1.

In this embodiment of the present invention, for example, formula 3 maybe used to adjust the network bandwidth threshold of each sub-index fileof the streaming media resource:

BANDWIDTH_(xadjusted)=BANDWIDTH_(x)×(1−log₂(BANDWIDTH_(x)/BANDWIDTH_(min))×0.05)  Formula3

-   -   where BANDWIDTH_(xadjusted) is a value obtained after        BANDWIDTH_(x) is adjusted, and a unit is bit/s.

Further, the bandwidth level of the detected network bandwidthW_(detected) obtained by means of periodic detection is determined byusing the method for determining the bandwidth level, of the sub-indexfile, corresponding to the first network bandwidth W₁ in step 101.

When BANDWIDTH_(xadjusted)≦W_(detected)<BANDWIDTH_(x+1ajdusted), it isdetermined that the detected network bandwidth W_(detected) is suitablefor downloading a streaming media resource corresponding toBANDWIDTH_(xadjusted), and a bandwidth level, of a streaming mediaresource, corresponding to W_(detected) is x; or whenBANDWIDTH_(xadjusted) is a maximum value of network bandwidth thresholdsof all sub-index files, if W_(detected)≧BANDWIDTH_(xadjusted), it isdetermined that the detected network bandwidth W_(detected) is suitablefor downloading a streaming media resource corresponding toBANDWIDTH_(xadjusted), and a bandwidth level, of a resource,corresponding to W_(detected) is x, where BANDWIDTH_(xadjusted) is anetwork bandwidth threshold of a sub-index file whose index value is x.

When it is determined that the bandwidth level corresponding toW_(detected) is x, the network bandwidth reduction times in the executedfirst media file downloading process may be further obtained accordingto the method in step 202.

The first network bandwidth level i is compared with the bandwidth levelx corresponding to the detected network bandwidth W_(detected). If i>x,the network bandwidth reduction times in the first media filedownloading process are increased by 1, and the network bandwidthreduction times in the first media file downloading process areaccumulated.

A network bandwidth threshold of each streaming media resource isdownward adjusted. Therefore, when a reduction degree of detectednetwork bandwidth is not high, a streaming media resource which thedetected network bandwidth is suitable for playing is still a streamingmedia resource being downloaded. Therefore, the streaming media resourcematching the detected network bandwidth is not directly switched whenthe detected network bandwidth is reduced. Therefore, a switch point ofthe streaming media resource is buffered, accuracy of streaming mediaresource switching is improved, and switching times are reduced.

FIG. 3 is a flowchart of another streaming media resource downloadingmethod according to an embodiment of the present invention.

The method includes the following steps.

Step 301: Determine that a first media file is a to-be-downloaded mediafile according to first network bandwidth. Step 301 is the same as step101 in the embodiment shown in FIG. 1, and details are not describedherein again.

Step 302: After an (n−1)^(th) data block in the first media file isdownloaded, and before an n^(th) data block in the first media file isdownloaded, obtain network bandwidth reduction times in an executedfirst media file downloading process.

The network bandwidth reduction times in the executed first media filedownloading process may be obtained by using the method in step 202 inthe embodiment shown in FIG. 2.

After the reduction times are obtained in step 302, a length of ato-be-downloaded data block is determined according to the reductiontimes. Specifically, step 303, step 304, or step 305 may be executedaccording to the reduction times after step 302.

Step 303: When the network bandwidth reduction times in the executedfirst media file downloading process are equal to 0, determine that alength of the to-be-downloaded n^(th) data block is equal to a presetlength, and start to download the n^(th) data block according to thedetermined preset length of the to-be-downloaded n^(th) data block. Thepreset length is obtained by using the method in step 102, and thelength is determined according to a network bandwidth threshold of asub-index file in a streaming media resource in which the first mediafile is located.

Step 304: When the network bandwidth reduction times in the executedfirst media file downloading process are greater than 0 and less than apreset threshold w, determine that a length of the to-be-downloadedn^(th) data block is less than a preset length, and download the n^(th)data block by using a reduced length of the data block.

The reduced length of the data block is determined by the networkbandwidth reduction times in the executed first media file downloadingprocess, and more reduction times indicate a smaller length of theto-be-downloaded n^(th) data block. Alternatively, the reduced length ofthe data block is determined by a time difference between a currentmoment to a moment of starting to download the first media file, and alarger time difference indicates a smaller length of theto-be-downloaded n^(th) data block.

For example, when the reduction times are 1, the reduced length of thedata block is P_(i)/(1+1) or P_(i)/(1+2); or when the time differencebetween the current moment and the moment of starting to download thefirst media file is two seconds, the reduced length of the data block isP_(i)/2 or P_(i)/(2+1).

Step 305: When the network bandwidth reduction times in the executedfirst media file downloading process are greater than or equal to apreset threshold w, stop downloading the first media file, and determinethat a length of a to-be-downloaded data block in the first media fileis 0.

It should be noted that after it is determined that the length of theto-be-downloaded data block in the first media file is 0 in step 305, itindicates that the first media file is no longer downloaded.

Further, the method provided in this embodiment of the present inventionmay further include the following steps a1, a2, and a3.

Step a1: Determine that a second media file is a to-be-downloaded mediafile according to second network bandwidth, where the second networkbandwidth is network bandwidth when it is determined that the networkbandwidth reduction times are greater than or equal to the presetthreshold w; and the second media file is included in a streaming mediaresource corresponding to the second network bandwidth.

It should be noted that the method for determining that the first mediafile is a to-be-downloaded media file in the embodiment shown in FIG. 1may be used to determine that the second media file is ato-be-downloaded media file.

Step a2: After an (n−1)^(th) data block in the second media file isdownloaded, and before an n^(th) data block in the second media file isdownloaded, determine a length of the to-be-downloaded n^(th) data blockaccording to network bandwidth reduction times in an executed secondmedia file downloading process, where 1≦n≦N.

In the second media file downloading process, a method same as that fordownloading the first media file is used for downloading. For the methodfor downloading the first media file, refer to the foregoingembodiments.

Step a3: Download the n^(th) data block in the second media fileaccording to the determined length of the to-be-downloaded n^(th) datablock, or determine that another media file is a to-be-downloaded mediafile, and start to download the another media file.

It should be noted that during downloading of any media file, referencemay be made to the foregoing method for downloading the first mediafile.

The foregoing method provided in this embodiment of the presentinvention is a downloading method used when network bandwidth is reducedin a streaming media resource downloading process. Data blockdownloading with relatively small bandwidth is not affected when networkbandwidth increases. Therefore, when the network bandwidth increases, anexisting manner may be used. For example, after a first media file in astreaming media resource is downloaded, the first media file is directlyswitched to a second media file in another streaming media resource thatis corresponding to a current network bandwidth level for downloading,or another method well known by a person skilled in the art may be usedfor downloading a streaming media resource when network bandwidthincreases. Certainly, in a network bandwidth increase process, a methodsimilar to step 303, 304, or 305 may be used. As the network bandwidthincreases, a length of a data block is increased to adapt to a networkbandwidth change.

When network bandwidth changes within a large range or frequentlyfluctuates, a network bandwidth detection result obtained by using anetwork bandwidth estimation method has a large error, and consequently,a media file being downloaded needs to be frequently switched. In thisembodiment of the present invention, a length of a to-be-downloaded datablock in a first media file is adjusted according to network bandwidthreduction times in an executed first media file downloading process, sothat the length of the to-be-downloaded data block better adapts tonetwork bandwidth reduction. This avoids a resource waste caused byinaccurate switching of the first media file being downloaded because ofan inaccurate network bandwidth detection result.

The following gives a specific example for better understanding theforegoing implementation manners of the present invention.

An M3U8 index file of a streaming media resource is as follows:

#EXTM3U

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=55648,CODECS=“mp 4a.40.5”

-   -   00.m3u8    -   #EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=120320,RESOLUTION=176×144,CODECS=“avc1.42e00a,mp4a.40.5”    -   01.m3u8    -   #EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=294784,RESOLUTION=320×180,CODECS=“avc1.42e00d,mp4a.40.5”    -   02.m3u8    -   #EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=511360,RESOLUTION=400×224,CODECS=“avc1.4d4015,mp4a.40.5”    -   03.m3u8    -   #EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=809152,        RESOLUTION=480×270,CODECS=“avc1.4d4015,mp4a.40.5”    -   04.m3u8    -   #EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1343072,        RESOLUTION=640×360,CODECS=“avc1.4d401e,mp4a.40.5”    -   05.m3u8

where #EXTM3U is a flag bit of the m3u8 file; #EXT-X-STREAM-INF is anattribute information flag bit of a streaming media resource that isrepresented by the sub-index file; PROGRAM-ID refers to an identifier ofthe streaming media resource, and represents a same type of resources ofdifferent encoding formats; BANDWIDTH refers to a network bandwidththreshold suitable for playing the streaming media resource, and a unitis bit/s; RESOLUTION refers to resolution; CODECS refers to a type and aformat of the streaming media resource; i.m3u8 is a file name of thesub-index file, where i is an integer greater than or equal to 0 andrepresents an index value and a bandwidth level of the sub-index file,and larger i indicates a larger index value, a higher bandwidth level,and larger bandwidth.

For example, a method for downloading the streaming media resource mayinclude the following steps.

Step 1: Process a network bandwidth threshold of each sub-index file toobtain a preset length, of a data block, corresponding to a TS mediafile of each streaming media resource.

For example, normalization processing may be performed on the bandwidththresholds of all the sub-index files to obtain the preset length of thedata block. Calculation according to a sequence of index values of thesub-index files is as follows:

-   -   P₀=log₂ (55648/55648)×10240=0    -   P₁=log₂ (120320/55648)×10240=11391    -   P₂=log₂(294784/55648)×10240=24629    -   P₃=log₂ (511360/55648)×10240=33879    -   P₄=log₂ (809152/55648)×10240=39546    -   P₅=log₂ (1343072/55648)×10240=47032

The foregoing results are results obtained after rounding processing,and a unit is byte (Byte).

In this embodiment of the present invention, a value range is limitedfor the preset length P₁ of the data block, the preset length has amaximum value and a minimum value, and 10240≦P_(i)≦65536. That is, whenP_(i) obtained by calculation is less than 10240, P_(i) is alwaysdetermined as 10240; or when P_(i) obtained by calculation is greaterthan 65536, P_(i) is always determined as 65536. Therefore, in theforegoing results, only P₀ needs to be processed, so that P₀=10240, andall other values are obtained after the calculation results are rounded.Therefore, the preset lengths of the data blocks of all the sub-indexfiles are respectively {10240, 11391, 24629, 33879, 39546, 47032},corresponding network bandwidth is respectively {55648, 120320, 294784,511360, 809152, 1343072}, and corresponding index values and bandwidthlevels are respectively {0, 1, 2, 3, 4, 5}.

For example, when detected network bandwidth W_(detected)=150000, whichis greater than 120320 bit/s and less than 294784 bit/s, an index valueand a bandwidth level of a streaming media resource corresponding to thedetected network bandwidth are 1, and a preset length of ato-be-downloaded data block is 11391 Bytes.

Step 2: Determine that a first media file is a to-be-downloaded mediafile according to first network bandwidth.

When a streaming media resource is to be downloaded, first networkbandwidth W₁ is obtained according to a bandwidth estimation method. Inthis embodiment of the present invention, it is assumed that theobtained first network bandwidth W₁=1400000 bit/s. W₁ is compared withnetwork bandwidth thresholds of all sub-index files. W₁ is greater thana network bandwidth threshold 1343072 whose index value is 5, and thenetwork bandwidth threshold 1343072 whose index value is 5 is a maximumvalue in all the sub-index files. Therefore, it is determined that afirst media file in a streaming media resource whose index value is 5 isa to-be-downloaded media file according to the first network bandwidthW₁, and according to a processing result in step 1, a preset length47032 KBs, of a data block, corresponding to the index value 5 is usedto start to download the first media file. It is recorded that a time ofstarting to download the first media file is 08:00:00.000 (which isupdated when a new media file is downloaded), and may have a precisionof millisecond.

Step 3: Periodically detect network bandwidth in a first media filedownloading process, and adjust a detection period of periodic networkbandwidth detection.

Starting from completion of downloading of the first data block in thefirst media file, when there is still a data block that has not beendownloaded in the first media file, whether to execute periodic networkbandwidth detection is determined.

A time difference between a current moment and a last moment ofexecuting periodic bandwidth detection is detected, and whether theforegoing time difference is greater than or equal to the detectionperiod is determined. When there is no action of executing the last timeof periodic bandwidth detection, that is, no bandwidth detection is everexecuted in the first media file downloading process, a time differencebetween a current moment and a moment of starting to download the firstmedia file is obtained. When the time difference is greater than orequal to the detection period, periodic network bandwidth detection isexecuted.

It should be noted that the network bandwidth detection period may havea preset value. In the first media file downloading process, thedetection period may be adjusted according to a network bandwidthchange.

The following uses an example to describe detection period adjustment.

For example, the network bandwidth detection period is preset to Tseconds. In the executed first media file downloading process, if thenetwork bandwidth is reduced at a last time of executing periodicnetwork bandwidth detection, and a bandwidth level difference i−xbetween a bandwidth level i of the last time of periodic networkbandwidth detection and a bandwidth level x of the first networkbandwidth W₁ is greater than T, the bandwidth level difference (i−x)seconds is used as a detection period; or if i−x is less than or equalto T, the preset T is still used as the detection period.

For example, in the first media file downloading process, periodicnetwork bandwidth detection has been executed. During periodic detectionthat just ends, the network bandwidth is reduced, a bandwidth leveldifference between a bandwidth level of reduced network bandwidth andthe bandwidth level of the first network bandwidth is 2, and a presetdetection period is one second. In this case, the bandwidth leveldifference two seconds is used as a detection period for periodicnetwork bandwidth detection. That is, when a time difference between amoment at which periodic network bandwidth detection just ends and acurrent moment is two seconds, periodic network bandwidth detection at acurrent time is executed, and is unrelated to a to-be-downloaded datablock.

In the first media file downloading process, if periodic networkbandwidth detection is never executed, or periodic detection isexecuted, but it is detected that a difference between a bandwidth levelof reduced network bandwidth and the level of the first networkbandwidth is less than a preset period one second, the preset detectionperiod one second is used as the detection period for periodic networkbandwidth detection.

Step 4: Obtain network bandwidth reduction times in the first media filedownloading process according to a periodic network bandwidth detectionresult.

In a periodic network bandwidth detection process, network bandwidththresholds of all sub-index files may be directly used as a basis fordetermining a bandwidth level corresponding to a periodically detectednetwork bandwidth, so as to obtain the network bandwidth reductiontimes.

Optionally, adjusted network bandwidth thresholds of all sub-index filesmay be used as a basis for determining a bandwidth level correspondingto a periodically detected network bandwidth, so as to obtain thenetwork bandwidth reduction times.

The following uses an example for description of using the adjustednetwork bandwidth thresholds of all the sub-index files as a basis.Adjustment to the network bandwidth thresholds of all the sub-indexfiles is as follows, and a unit of an adjusted BANDWIDTH_(adjusted) isbits/s.

BANDWIDTH_(Oadjusted)=55648×(1−log₂(55648/55648)×0.05)=55648

BANDWIDTH_(1adjusted)=120320×(1−log₂(120320/55648)×0.05)=113100

BANDWIDTH_(2adjusted)=294784× (1−log₂(294784/55648)×0.05)=259409

BANDWIDTH_(3adjusted)=511360×(1−log₂(511360/55648)×0.05)=429542

BANDWIDTH_(4adjusted)=809152×(1−log₂(809152/55648)×0.05)=655413

BANDWIDTH_(5adjusted)=1343072×(1−log₂(1343072/55648)×0.05)=1034 165

The adjusted network bandwidth is respectively {55648, 113100, 259409,429542, 655413, 1034165}, corresponding network bandwidth isrespectively {55648, 120320, 294784, 511360, 809152, 1343072}, andcorresponding index values and bandwidth levels are respectively {0, 1,2, 3, 4, 5}.

When the detected network bandwidth W_(detected)=450000 bits/s,W_(detected) is compared with the adjusted network bandwidth.W_(detected) is greater than the adjusted network bandwidth threshold425942 whose index value is 3, and W_(detected) is less than theadjusted network bandwidth threshold 655413 whose index value is 4. Inthis case, BANDWIDTH_(3adjusted)<W_(detected)<BANDWIDTH_(4adjusted).Therefore, the periodically detected network bandwidth W_(detected) iscorresponding to a streaming media resource whose index value is 3.

The index value 5 corresponding to the first network bandwidth iscompared with the index value 3 corresponding to the periodicallydetected network bandwidth W_(detected). It can be learned that theperiodically detected network bandwidth W_(detected) is reduced comparedwith the first network bandwidth W. Therefore, a difference value of theindex values is recorded as 2, the network bandwidth reduction times inthe first media file downloading process are increased by 1, and thenetwork bandwidth reduction times in the first media file downloadingprocess are accumulated.

Step 5: After an (n−1)^(th) data block is downloaded, and before ann^(th) data block is downloaded, determine a length of theto-be-downloaded n^(th) data block according to the network bandwidthreduction times that are in the first media file downloading process andthat are obtained in step 4, and start corresponding downloading.

If the reduction times obtained in step 4 are equal to 0, that is,network bandwidth is not reduced in a process of downloading the firstn−1 data blocks in the first media file, it is determined that thelength of the to-be-downloaded n^(th) data block is the preset length47032 KBs, and the first media file continues to be downloaded.

If the reduction times obtained in step 4 are 2, and a preset thresholdis 3, the reduction times are less than the preset threshold 3. That is,in the process of downloading the first n−1 data blocks in the firstmedia file, when the network bandwidth is reduced for two times, it maybe determined that the length of the to-be-downloaded data block is47032/2_((times)) KBs or 47032/(2_((times))+1) KBs according to the tworeduction times; or it is determined that the length of theto-be-downloaded data block is 47032/2 KBs according to a timedifference 2 between a time 08:00:02.020 to download the n^(th) datablock and the time 08:00:00.000 of starting to download the first mediafile. A terminal device may select, according to an actual requirement,a determined length of the data block from the foregoing results tostart to download the n^(th) data block. If the reduction times obtainedin step 4 are 3 that is greater than or equal to the preset threshold 3,that is, in the process of downloading the first n−1 data blocks in thefirst media file, when the network bandwidth is reduced for three times,it is excluded that network bandwidth detection is inaccurate, and it isdetermined that the network bandwidth is reduced. Therefore, thedownloading of the first media file and all downloaded data blocks areabandoned, and it is determined that a second media file in thestreaming media resource is a to-be-downloaded media file according tonew network bandwidth W_(new).

An embodiment of the present invention further provides a streamingmedia resource downloading apparatus that implements the steps and themethods in the foregoing method embodiments.

FIG. 4 is a schematic diagram of a streaming media resource downloadingapparatus according to an embodiment of the present invention. As shownin FIG. 4, a streaming media resource downloading apparatus 400includes: a first determining unit 401, a reduction times obtaining unit402, and a second determining unit 403, where

the first determining unit 401 is configured to determine that a firstmedia file is a to-be-downloaded media file according to first networkbandwidth.

The first network bandwidth is network bandwidth when it is determinedthat the first media file is a to-be-downloaded media file; and thefirst media file is included in a streaming media resource correspondingto the first network bandwidth, and the first media file includes N datablocks, where N≧2, and N is an integer.

The reduction times obtaining unit 402 is configured to obtain networkbandwidth reduction times in an executed first media file downloadingprocess; and

the second determining unit 403 is configured to: after an (n−1)^(th)data block in the first media file is downloaded, and before an n^(th)data block in the first media file is downloaded, determine a length ofthe to-be-downloaded n^(th) data block according to the networkbandwidth reduction times that are in the executed first media filedownloading process and that are obtained by the reduction timesobtaining unit 502, where n≧2.

Further, when obtaining the network bandwidth reduction times in theexecuted first media file downloading process, the reduction timesobtaining unit 402 obtains the network bandwidth reduction timesaccording to the following rules:

when i−x>0, increasing the network bandwidth reduction times by 1;

where i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, and bandwidth corresponding toi is greater than bandwidth corresponding to x.

Further, when determining the length of the to-be-downloaded n^(th) datablock according to the network bandwidth reduction times that are in theexecuted first media file downloading process and that are obtained bythe reduction times obtaining unit 402, the second determining unit 403is specifically configured to:

when the network bandwidth reduction times in the executed first mediafile downloading process are equal to 0, determine that the length ofthe to-be-downloaded n^(th) data block is a preset length, where thepreset length is corresponding to the first media file; or

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than 0 and less than a firstthreshold, determine that the length of the to-be-downloaded n^(th) datablock is less than a preset length; or

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than or equal to a first threshold,stop downloading the first media file. In addition, the firstdetermining unit 401 determines that a second media file is ato-be-downloaded media file according to second network bandwidth, wherethe second network bandwidth is network bandwidth when it is determinedthat the network bandwidth reduction times are greater than or equal tothe first threshold; and the second media file is included in astreaming media resource corresponding to the second network bandwidth.

Further, the second determining unit 403 uses the following rules whendetermining that the length of the to-be-downloaded n^(th) data block isthe preset length:

when there are more network bandwidth reduction times in the executedfirst media file downloading process, determining that the length of then^(th) data block is smaller; or

when there is a larger time difference between a current moment and amoment of starting to download the first media file, determining thatthe length of the n^(th) data block is smaller.

In this embodiment of the present invention, in a downloading process,it is determined, according to network bandwidth reduction times in afirst media file downloading process, that a length of ato-be-downloaded data block can adapt to a requirement, of reducednetwork bandwidth, on the length of the to-be-downloaded data block, andtimes of resource downloading switching are reduced. This avoids aresource waste, and video playing is smooth.

The streaming media resource downloading apparatus provided in thisembodiment of the present invention is configured to implement themethods shown in the embodiments shown in FIG. 1 to FIG. 3. For detailsof a working principle and a working process of the streaming mediaresource downloading apparatus, and of a technical effect generated bythe streaming media resource downloading apparatus, refer to theembodiments shown in FIG. 1 to FIG. 3, and details are not describedherein.

FIG. 5 is a schematic diagram of another streaming media resourcedownloading apparatus according to an embodiment of the presentinvention. On the basis of the embodiment shown in FIG. 4, as shown inFIG. 5, the streaming media resource downloading apparatus 500 furtherincludes a detection unit 501.

The detection unit 501 is configured to periodically detect networkbandwidth in the first media file downloading process.

The reduction times obtaining unit 402 is configured to obtain thenetwork bandwidth reduction times in the executed first media filedownloading process according to the network bandwidth periodicallydetected by the detection unit 501.

In the first media file downloading process, the detection unit 501constantly and periodically detects network bandwidth at a currentmoment. When a time difference between a current moment and a last timeof network bandwidth detection is greater than or equal to a detectionperiod, the detection unit 501 executes network bandwidth detection atthe current time, and the reduction times obtaining unit 402 obtains thenetwork bandwidth reduction times in the executed first media filedownloading process according to a network bandwidth result periodicallydetected by the detection unit 501.

Further, the streaming media resource downloading apparatus 500 furtherincludes a data block downloading unit 502.

The data block downloading unit 502 is configured to: after the seconddetermining unit 403 determines the length of the to-be-downloadedn^(th) data block, download the n^(th) data block according to thelength, of the n^(th) data block, determined by the second determiningunit.

Further, the streaming media resource downloading apparatus 500 furtherincludes a period calculation unit 503 and a bandwidth level determiningunit 504.

The period calculation unit 503 is configured to calculate a detectionperiod of periodic network bandwidth detection in the first media filedownloading process. The detection unit 501 may execute networkbandwidth detection according to the detection period obtained by theperiod calculation unit 503 by calculation.

The period calculation unit 503 may determine the detection period inthe following manner:

when i−x>k, determining that T_(m+1)>T; or

when 0≦i−x<k, determining that T_(m+1)=T;

where i is the bandwidth level corresponding to the first networkbandwidth, and x is the bandwidth level corresponding to the networkbandwidth detected at the m^(th) time, where the bandwidth level is aninteger, m is an integer greater than or equal to 1, the bandwidthcorresponding to i is greater than the bandwidth corresponding to x, andk is a preset threshold for changing the detection period; and

T is the network bandwidth detection period, and T_(m+1) is a networkbandwidth detection period at an (m+1)^(th) time, whereT_(m+1)=t_(m+1)−t_(m), t_(m+1) is a network bandwidth detection momentat the (m+1)^(th) time, and t_(m) is a network bandwidth detectionmoment at the m^(th) time.

The bandwidth level determining unit 504 is configured to determine, inthe following manner, a bandwidth level corresponding to a networkbandwidth detected by the detection unit 501:

A streaming media resource includes multiple streaming media resourceshaving different network bandwidth thresholds; a network bandwidththreshold is included in a sub-index file of a streaming media resource,and is corresponding to a bandwidth level of the streaming mediaresource; and

when W_(i)×a≦W_(detected)<W_(i+1)×b, it is determined that the bandwidthlevel corresponding to the detected network bandwidth is i, where

W_(detected) is the detected network bandwidth, W_(i) is a networkbandwidth threshold corresponding to the bandwidth level i, and W_(i+1)is a network bandwidth threshold corresponding to a bandwidth level i+1,where 0<a<1, and 0<b<1.

When network bandwidth frequently changes, a network bandwidth detectionresult obtained by using a network bandwidth estimation method has alarge error, and consequently, a media file being downloaded needs to befrequently switched. In this embodiment of the present invention, alength of a to-be-downloaded data block in a first media file isdetermined according to network bandwidth reduction times in an executedfirst media file downloading process, so that a to-be-downloadedstreaming media resource can better adapt to network bandwidthreduction. This avoids a resource waste caused by inaccurate switchingof a streaming media resource being downloaded because of an inaccuratenetwork bandwidth detection result, and accuracy of a network bandwidthdetection result is improved.

The streaming media resource downloading apparatus provided in thisembodiment of the present invention is configured to implement themethods shown in the embodiments shown in FIG. 1 to FIG. 3. For detailsof a working principle and a working process of the streaming mediaresource downloading apparatus, and of a technical effect generated bythe streaming media resource downloading apparatus, refer to theembodiments shown in FIG. 1 to FIG. 3, and details are not describedherein.

FIG. 6 is a schematic diagram of a terminal device according to anembodiment of the present invention.

A terminal device 600 in this embodiment of the present inventionincludes a processor 601 coupled to one or more data storageapparatuses, a data storage apparatus 602, a communications interface603, and a bus 604.

The data storage apparatus 602 may include a storage medium and a memoryunit. The storage medium may be read-only, such as a read-only memory(ROM), or may be readable/writable, such as a hard disk or a flashmemory. The memory unit may be a random access memory (RAM). The memoryunit may be physically integrated with the processor 601, or integratedinto the processor 601, or may be constructed in one or more independentunits.

The processor 601 is a control center of the terminal device 600, andprovides a ranking and processing facility to execute an instruction,execute an interruption operation, and provide a timing function andmany other functions. Optionally, the processor 601 includes one or morecentral processing units (CPU), and optionally, the terminal device 600includes at least one processor. The processor 601 may be a single-core(single-CPU) processor or a multi-core (multi-CPU) processor. The term“processor” used in this specification refers to one or more devices,circuits, and/or processing cores that are used to process data such asa computer program instruction.

The processor 601 may execute program code stored in the data storageapparatus 602. Optionally, the program code stored in the storage mediumof the data storage apparatus 602 may be copied to the memory unit forexecution by the processor. The processor may execute at least onekernel (for example, a kernel in operating systems sold in trademarkssuch as LINUZ™, UNIX™, WINDOWS™, ANDROID™, and IOS™). As is known toall, the kernel is used to control an operation of the terminal device600 by controlling execution of another program or process, controllingcommunication with a peripheral device, and controlling use of acomputing device resource.

The terminal device 600 further includes the communications interface603, configured to communicate with another device or system directly orby using an external network.

The foregoing elements of the terminal device 600 may be coupled to eachother by using any one or any combination of buses 604 such as a databus, an address bus, a control bus, an extended bus, and a local bus.

Optionally, the terminal device 600 further includes an output deviceand an input device (which are not shown in the figure). The outputdevice is coupled to the processor 601, and can display information inone or more manners. An example of the output device is a visual displayunit, such as a liquid crystal display (LCD), a light-emitting diode(LED) display, a cathode ray tube (CRT), or a projector. The inputdevice is also coupled to the processor 601, and can receive input froma user of the terminal device 600 in one or more manners. An example ofthe input device includes a mouse, a keyboard, a touchscreen device, asensor device, or the like.

The terminal device 600 may be a general computing device or anapplication-specific computing device. As a practical example, theforegoing terminal device 600 may be a desktop computer, a notebookcomputer, a network server, a personal digital assistant (PDA), a mobilephone, a tablet computer, a wireless terminal device, atelecommunications device, an embedded system, or any another devicehaving a structure similar to that in FIG. 6. However, the presentinvention is not limited to merely any specific type of terminal device.

According to the terminal device 600 in this embodiment of the presentinvention, when the processor 601 executes an instruction of the programcode in the data storage apparatus, the instruction instructs theprocessor 601 to execute the following operations:

determining that a first media file is a to-be-downloaded media fileaccording to first network bandwidth, where the first network bandwidthis network bandwidth when it is determined that the first media file isa to-be-downloaded media file; and the first media file is included in astreaming media resource corresponding to the first network bandwidth,and the first media file includes N data blocks, where N≧2, and N is aninteger; and after an (n−1)^(th) data block in the first media file isdownloaded, and before an n^(th) data block in the first media file isdownloaded, the processor 601 determines a length of theto-be-downloaded n^(th) data block according to network bandwidthreduction times in an executed first media file downloading process,where 1≦n≦N.

Further, the processor 601 in this embodiment of the present inventionfurther executes the following operations:

periodically detecting network bandwidth in the first media filedownloading process to obtain periodically detected network bandwidth;and obtaining the network bandwidth reduction times in the executedfirst media file downloading process according to the periodicallydetected network bandwidth.

Further, the processor 601 in this embodiment of the present inventiondetermines, in the following manner, a bandwidth level corresponding toa detected network bandwidth: A streaming media resource includesmultiple streaming media resources having different network bandwidththresholds; a network bandwidth threshold is included in a sub-indexfile of a streaming media resource, and is corresponding to a bandwidthlevel of the streaming media resource; whenW_(i)×a≦W_(detected)<W_(i+1)×b, it is determined that the bandwidthlevel corresponding to the detected network bandwidth is i, whereW_(detected) is the detected network bandwidth, W_(i) is a networkbandwidth threshold corresponding to the bandwidth level i, and W_(i+1)is a network bandwidth threshold corresponding to a bandwidth level i+1,where 0<a<1, and 0<b<1.

Further, when executing periodic network bandwidth detection in thefirst media file downloading process, the processor 601 in thisembodiment of the present invention determines a detection period in thefollowing manner:

when i−x≧k, determining that T_(m+1)>T; or

when 0≦i−x<k, determining that T_(m+1)=T;

where i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, bandwidth corresponding to iis greater than bandwidth corresponding to x, and k is a preset secondthreshold; and

T is a preset network bandwidth detection period, and T_(m+1) is anetwork bandwidth detection period at an (m+1)^(th) time, whereT_(m+1)=t_(m+1)−t_(m), t_(m+1) is a network bandwidth detection momentat the (m+1)^(th) time, and t_(m) is a network bandwidth detectionmoment at the m^(th) time.

Further, the processor 601 in this embodiment of the present inventionobtains the network bandwidth reduction times according to the followingrules:

when i−x>0, increasing the network bandwidth reduction times by 1, where

i is the bandwidth level corresponding to the first network bandwidth,and x is the bandwidth level corresponding to the network bandwidthdetected at the m^(th) time, where the bandwidth level is an integer, mis an integer greater than or equal to 1, and the bandwidthcorresponding to i is greater than the bandwidth corresponding to x.

Further, that the processor 601 in this embodiment of the presentinvention determines the length of the to-be-downloaded n^(th) datablock according to the network bandwidth reduction times in the executedfirst media file downloading process specifically includes:

When the network bandwidth reduction times in the executed first mediafile downloading process are equal to 0, the processor 601 determinesthat the length of the to-be-downloaded data block is equal to thepreset length of the to-be-downloaded data block, and starts to downloadthe to-be-downloaded data block; or

when the network bandwidth reduction times in the executed first mediafile downloading process are greater than or equal to 0, and less than apreset threshold w, the processor 601 reduces the length of theto-be-downloaded data block, so that the length of the to-be-downloadeddata block is less than the preset length of the to-be-downloaded datablock, and continues to download the to-be-downloaded data block in thefirst media file.

The processor 601 may adjust the length of the to-be-downloaded datablock according to the network bandwidth reduction times in the executedfirst media file downloading process or a time difference between acurrent moment to a moment of starting to download the first media file.More reduction times or a larger time difference indicates a smallerlength of the to-be-downloaded data block.

When the network bandwidth reduction times in the executed first mediafile downloading process are greater than or equal to the presetthreshold w, the processor 601 stops downloading the first media file,and determines that the length of the to-be-downloaded data block in thefirst media file is 0.

The processor 601 executes the following steps: determines that a secondmedia file is a to-be-downloaded media file according to second networkbandwidth, where the second network bandwidth is network bandwidth whenit is determined that the network bandwidth reduction times are greaterthan or equal to the preset threshold w; and the second media file isincluded in a streaming media resource corresponding to the secondnetwork bandwidth.

According to the terminal device in this embodiment of the presentinvention, a processor adjusts a length of a to-be-downloaded data blockin a first media file according to network bandwidth reduction times inan executed first media file downloading process, so that ato-be-downloaded streaming media resource better adapts to networkbandwidth reduction. This avoids a resource waste caused by inaccurateswitching of a streaming media resource being downloaded because of aninaccurate network bandwidth detection result, and accuracy of a networkbandwidth detection result is improved.

The terminal device provided in this embodiment of the present inventionis configured to implement the methods shown in the embodiments shown inFIG. 1 to FIG. 3. For details of a working principle and a workingprocess of the terminal device, and of a technical effect generated bythe terminal device, refer to the embodiments shown in FIG. 1 to FIG. 3,and details are not described herein.

With descriptions of the foregoing embodiments, a person skilled in theart may clearly understand that the present invention may be implementedby hardware, firmware or a combination thereof. When the presentinvention is implemented by software, the foregoing functions may bestored in a computer-readable medium or transmitted as one or moreinstructions or code in the computer-readable medium. Thecomputer-readable medium includes a computer storage medium and acommunications medium, where the communications medium includes anymedium that enables a computer program to be transmitted from one placeto another. The storage medium may be any available medium accessible toa computer. The following provides an example but does not impose alimitation: The computer-readable medium may include a RAM, a ROM, anEEPROM, a CD-ROM, or another optical disc storage or disk storagemedium, or another magnetic storage device, or any other medium that cancarry or store expected program code in a form of an instruction or adata structure and can be accessed by a computer. In addition, anyconnection may be appropriately defined as a computer-readable medium.For example, if software is transmitted from a website, a server oranother remote source by using a coaxial cable, an optical fiber/cable,a twisted pair, a digital subscriber line (DSL) or wireless technologiessuch as infrared ray, radio and microwave, the coaxial cable, opticalfiber/cable, twisted pair, DSL or wireless technologies such as infraredray, radio and microwave are included in fixation of a medium to whichthey belong. For example, a disk (Disk) and disc (disc) used by thepresent invention includes a compact disc CD, a laser disc, an opticaldisc, a digital versatile disc (DVD), a floppy disk and a Blu-ray disc,where the disk generally copies data by a magnetic means, and the disccopies data optically by a laser means. The foregoing combination shouldalso be included in the protection scope of the computer-readablemedium.

In summary, what is described above is merely examples of embodiments ofthe technical solutions of the present invention, but is not intended tolimit the protection scope of the present invention. Any modification,equivalent replacement, or improvement made without departing from thespirit and principle of the present invention shall fall within theprotection scope of the present invention.

What is claimed is:
 1. A streaming media resource downloading method,comprising: determining that a first media file is a to-be-downloadedmedia file according to a first network bandwidth, wherein the firstnetwork bandwidth is network bandwidth when it is determined that thefirst media file is a to-be-downloaded media file, the first media fileis comprised in a streaming media resource corresponding to the firstnetwork bandwidth, and the first media file comprises N data blocks,wherein N≧2, and N is an integer; and after an (n−1)^(th) data block inthe first media file is downloaded, and before an n^(th) data block inthe first media file is downloaded, determining a length of theto-be-downloaded n^(th) data block according to network bandwidthreduction times in an executed first media file downloading process,wherein 1≦n≦N.
 2. The method according to claim 1, further comprising:periodically detecting network bandwidth in the first media filedownloading process; and obtaining the network bandwidth reduction timesin the executed first media file downloading process according to theperiodically detected network bandwidth.
 3. The method according toclaim 1, wherein determining a length of the to-be-downloaded n^(th)data block according to network bandwidth reduction times in an executedfirst media file downloading process comprises: when the networkbandwidth reduction times in the executed first media file downloadingprocess are equal to 0, determining that the length of theto-be-downloaded n^(th) data block is a preset length, wherein thepreset length is corresponding to the first media file; or when thenetwork bandwidth reduction times in the executed first media filedownloading process are greater than 0 and less than a first threshold,determining that the length of the to-be-downloaded n^(th) data block isless than a preset length, wherein the preset length is corresponding tothe first media file.
 4. The method according to claim 3, furthercomprising: when the network bandwidth reduction times in the executedfirst media file downloading process are greater than 0 and less thanthe first threshold, using the following rules to determine the lengthof the to-be-downloaded n^(th) data block: when there are more networkbandwidth reduction times in the executed first media file downloadingprocess, determining that the length of the n^(th) data block issmaller; or when there is a larger time difference between a currentmoment and a moment of starting to download the first media file,determining that the length of the n^(th) data block is smaller.
 5. Themethod according to claim 1, wherein after determining a length of theto-be-downloaded n^(th) data block, the method further comprises:downloading the n^(th) data block according to the determined length ofthe n^(th) data block.
 6. The method according to claim 1, furthercomprising: when the network bandwidth reduction times in the executedfirst media file downloading process are greater than or equal to thefirst threshold, stopping downloading the first media file; anddetermining that a second media file is a to-be-downloaded media fileaccording to a second network bandwidth, wherein the second networkbandwidth is network bandwidth when it is determined that the networkbandwidth reduction times are greater than or equal to the firstthreshold and the second media file is comprised in a streaming mediaresource corresponding to the second network bandwidth.
 7. The methodaccording to claim 2, further comprising: when the network bandwidth inthe first media file downloading process is periodically detected,determining a detection period in the following manner: when i−x≧k,determining that T_(m+1)>T; or when 0≦i−x<k, determining that T_(m+1)=T;wherein i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, wherein the bandwidth level is an integer, mis an integer greater than or equal to 1, bandwidth corresponding to iis greater than bandwidth corresponding to x, and k is a preset secondthreshold; and T is a preset detection period, and T_(m+i) is a networkbandwidth detection period at an (m+1)^(th) time, whereinT_(m+1)=t_(m)+1−t_(m), t_(m+1) is a network bandwidth detection momentat the (m+1)^(th) time, and t_(m) is a network bandwidth detectionmoment at the m^(th) time.
 8. The method according to claim 2, furthercomprising: obtaining the network bandwidth reduction times according tothe following rules: when i−x>0, increasing the network bandwidthreduction times by 1, wherein i is the bandwidth level corresponding tothe first network bandwidth, and x is the bandwidth level correspondingto the network bandwidth detected at the m^(th) time, wherein thebandwidth level is an integer, m is an integer greater than or equal to1, and the bandwidth corresponding to i is greater than the bandwidthcorresponding to x.
 9. The method according to claim 7, furthercomprising: determining, in the following manner, a bandwidth levelcorresponding to a detected network bandwidth: the streaming mediaresource comprises multiple media files that are respectivelycorresponding to different bandwidth levels; each bandwidth level iscorresponding to one network bandwidth threshold; and whenW_(i)×a≦W_(detected)<W_(i+1)×b, it is determined that the bandwidthlevel corresponding to the detected network bandwidth is i, whereinW_(detected) is the detected network bandwidth, W_(i) is a networkbandwidth threshold corresponding to the bandwidth level i, and W₁₊₁ isa network bandwidth threshold corresponding to a bandwidth level i+1,wherein 0<a<1, and 0<b<1. 10-18. (canceled)
 19. A tell Anal device,comprising: a processor; a data storage apparatus; a communicationsinterface; wherein the processor, the data storage apparatus, and thecommunications interface are configured to communicate with each otherby using a bus; and wherein the processor reads program code stored inthe data storage apparatus, and the program code, when executed by theprocessor, causes the processor to: determine that a first media file isa to-be-downloaded media file according to a first network bandwidth,wherein the first network bandwidth is network bandwidth when it isdeter mined that the first media file is a to-be-downloaded media file,the first media file is comprised in a streaming media resourcecorresponding to the first network bandwidth, and the first media filecomprises N data blocks, wherein N≧2, and N is an integer, and after an(n−1)^(th) data block in the first media file is downloaded, and beforean n^(th) data block in the first media file is downloaded, determine alength of the to-be-downloaded n^(th) data block according to networkbandwidth reduction times in an executed first media file downloadingprocess, wherein 1≦n≦N.
 20. The terminal device according to claim 19,wherein the program code, when executed by the processor, causes theprocessor to: periodically detect network bandwidth in the first mediafile downloading process; and obtain the network bandwidth reductiontimes in the executed first media file downloading process according tothe periodically detected network bandwidth.
 21. The terminal deviceaccording to claim 19, wherein to determine the length of theto-be-downloaded n^(th) data block according to the network bandwidthreduction times in the executed first media file downloading process,the program code, when executed by the processor, causes the processorto: when the network bandwidth reduction times in the executed firstmedia file downloading process are equal to 0 determine that the lengthof the to-be-downloaded n^(th) data block is a preset length, whereinthe preset length is corresponding to the first media file; or when thenetwork bandwidth reduction times in the executed first media filedownloading process are greater than 0 and less than a first threshold,determine that the length of the to-be-downloaded n^(th) data block isless than a preset length, wherein the preset length is corresponding tothe first media file.
 22. The terminal device according to claim 21,wherein when the network bandwidth reduction times in the executed firstmedia file downloading process are greater than 0 and less than thefirst threshold, the program code, when executed by the processor,causes the processor to use the following rules to determine the lengthof the to-be-downloaded n^(th) data block: when there are more networkbandwidth reduction times in the executed first media file downloadingprocess, determine that the length of the n^(th) data block is smaller;or when there is a larger time difference between a current moment and amoment of starting to download the first media file, determine that thelength of the n^(th) data block is smaller.
 23. The terminal deviceaccording to claim 19, wherein after determining the length of theto-be-downloaded n^(th) data block, the program code, when executed bythe processor, causes the processor to execute, according to thedetermined length of the n^(th) data block, an operation to download then^(th) data block.
 24. The terminal device according to claim 19,wherein the program code, when executed by the processor, further causesthe processor to: when the network bandwidth reduction times in theexecuted first media file downloading process are greater than or equalto the first threshold, stop downloading the first media file; anddetermine that a second media file is a to-be-downloaded media fileaccording to second network bandwidth, wherein the second networkbandwidth is network bandwidth when it is determined that the networkbandwidth reduction times are greater than or equal to the firstthreshold, and the second media file is comprised in a streaming mediaresource corresponding to the second network bandwidth.
 25. The terminaldevice according to claim 20, wherein to periodically detect networkbandwidth in the first media file downloading process, the program code,when executed by the processor, causes the processor to: when i−x≧k,determine that T_(m+1)>T; or when 0≦i−x≦k, determine that T_(m+1)=T;wherein i is a bandwidth level corresponding to the first networkbandwidth, and x is a bandwidth level corresponding to network bandwidthdetected at an m^(th) time, wherein the bandwidth level is an integer, mis an integer greater than or equal to 1, bandwidth corresponding to iis greater than bandwidth corresponding to x, and k is a preset secondthreshold; and T is a preset detection period, and T_(m+1) is a networkbandwidth detection period at an (m+1)^(th) time, whereinT_(m+1)=t_(m+1)−t_(m), t_(m+1) is a network bandwidth detection momentat the (m+1)^(th) time, and t_(m) is a network bandwidth detectionmoment at the m^(th) time.
 26. The terminal device according to claim20, wherein to obtain the network bandwidth reduction times the programcode, when executed by the processor, causes the processor to: wheni−x>0, increase the network bandwidth reduction times by 1, wherein i isthe bandwidth level corresponding to the first network bandwidth, and xis the bandwidth level corresponding to the network bandwidth detectedat the m^(th) time, wherein the bandwidth level is an integer, m is aninteger greater than or equal to 1, and the bandwidth corresponding to iis greater than the bandwidth corresponding to x.
 27. The terminaldevice according to claim 25, wherein to determine a bandwidth levelcorresponding to a detected network bandwidth, the program code, whenexecuted by the processor, causes the processor to: whenW_(i)×a≦W_(detected)<W_(i+1)×b, determine that the bandwidth levelcorresponding to the detected network bandwidth is i, wherein:W_(detected) is the detected network bandwidth, W, is a networkbandwidth threshold corresponding to the bandwidth level i, and W_(i+1)is a network bandwidth threshold corresponding to a bandwidth level i+1,wherein 0<a<1, and 0<b<1, the streaming media resource comprisesmultiple media files that are respectively corresponding to differentbandwidth levels, and each bandwidth level is corresponding to onenetwork bandwidth threshold.